In recent years, as bandwidths have broadened in comparison to preceding analog networks as the digitalization of networks such as ISDN and ASDL advances, systems for transmitting and receiving image data over networks have rapidly widespread. As one such system, there is a remote monitoring system enabling observation at one location of images from a plurality of cameras arranged remotely. With this remote monitoring system, typically, one of the camera images being observed by an observer is selected, and the photographing direction for the selected camera image is made to be controllable.
A screen example for this typical remote monitoring system is shown in FIG. 1. Screen 10 of a remote monitoring system shown in FIG. 1 is composed of image display region 11 that displays images for a plurality of remotely arranged cameras, camera select region 12 that selects a camera to display an image from the plurality of installed cameras, and camera control region 13 that controls the camera selected by camera select region 12. The user observing the image can observe locations where the user wants to see from those displayed at camera select region 12 by clicking icon 14 so as to switch over between cameras.
A configuration for this kind of remote monitoring system is shown in FIG. 2. The remote monitoring system shown in FIG. 2 is composed of a plurality of cameras 20a to 20n installed remotely, camera control apparatus 21 that receives and plays back images from cameras 20a to 20n and controls the photographing direction and zoom magnification etc. of cameras 20a to 20n, monitor 22 that displays camera images, and pointing device 23 such as a mouse etc. that controls cameras 20a to 20n and instructs images for display.
Camera control apparatus 21 is configured from camera image switching section 24 that receives images from the plurality of cameras 20a to 20n and switches images by instructions from the user, image display section 25 that displays images of cameras 20a to 20n at monitor 22, camera control instruction receiving section 26 switching camera images to be displayed and receiving instructions from a user for controlling photographing direction and zoom magnification of a camera, and camera control section 27 that instructs for controlling to cameras 20a to 20n and that instructs for switching of images to be displayed at camera image switching section 24.
With this kind of remote monitoring system, a user designates cameras 20a to 20n which the user wants to observe from the plurality of cameras 20a to 20n from camera select region 12 shown in FIG. 1 by pointing device 23. camera control instruction receiving section 26 then receives a control instruction from a user and reports the instruction to camera control section 27. Camera control section 27 stores that an instruction for camera control received from camera control instruction receiving section 26 is for a camera designated by a user, and instructs switching of an image of a camera displayed at monitor 22 to camera image switching section 24. Camera image switching section 24 sends an image for which an instruction is received from camera control section 27 to image display section 25 and image display section 25 displays this image at monitor 22.
FIG. 1 is for the case of a configuration displaying just one image for a camera of the images for the plurality of cameras 20a to 20n but monitoring systems displaying a plurality of camera images at the same time also exist, as shown in FIG. 3. This kind of display method has the drawback that it is not possible to observe detailed portions of the image because the display region for an image for each one camera is small. However, it is possible for a user to view an image which the user wants to see without instructing for switching over to this image by moving their line of sight. In this case, in order to select the camera the user wants to control, it is general to click image 30 that is being displayed instead of camera selection region 12 of FIG. 1.
Further, as a method for selecting one camera of a plurality of existing cameras, methods exist where, as shown in FIG. 4, a location where a camera is installed is shown on a map by an icon, with a user then selecting an icon on the map (see, for example, Patent Document 1).
The camera control apparatus shown in FIG. 4 includes map 40 that displays icons at locations where cameras are installed, image display region 42 that displays the selected camera image, and camera control region 43 that controls the selected camera. Icon 41 on map 40 displaying the d photographing direction and field of view of the camera is selected, and a user can then display an image which the user wants to see by controlling a straight line indicating a boundary line of the Field of view and a photographing direction of the camera by a pointing device.
FIG. 5 is an outline view showing the state of a camera image before and after switching at the time of switching over cameras by the method of the related art. FIG. 5A shows the state of a camera image before switching, and FIG. 5B shows a camera image at the moment that the image is switched to the instructed camera as a result of a user clicking on icon 50 by a pointing device etc.
Patent Document 1: Japanese Patent Application Laid-Open No. HEI9-289607.